The only way to fight for an advantage.
9... b4e7  10. e3d4  10... d8c7 I didn't know this move. I used to play 10...d6, when White is slightly better but it's not a big deal. 11. f1e1 This prevents 11...Ng4, which can simply be answered by 12.h3, but allows Black to play 11...d5. 11... d7d5 